The present invention relates to a data encryption system and, more particularly, to a data encryption system for a micro control system.
It is known to utilize data encryption in a variety of postal funds and other systems. The algorithm for data encryption may be represented by a standard such as, the Data Encryption Standard, United States Federal Information Processing Standards Publication 46, dated Jan. 15, 1977. The Data Encryption Standard (DES) describes a data encryption algorithm for implementation in special purpose electronic devices, such as electronic postage metering devices. The algorithm is designed to encipher and decipher blocks of data comprised of 64 bits under the control of a 64-bit key. Deciphering is accomplished by using the same key as for enciphering, but with the schedule of addressing the key bit altered so that the deciphering process is the reverse of the enciphering process.